The present invention relates to concrete support structures and in particular relates to multi-sectioned concrete support structures exhibiting high strength and corrosion resistance.
Concrete is widely used as a medium to form support structures in a number of different applications. For instance, foundations, support pilings, beams, and containers are just a few examples of concrete support structures which have been used in a variety of construction applications, ranging from bridge erection to nuclear power plant construction.
In its conventional form, concrete consists of aggregate, cement, and sand, and weighs approximately 4,040 lbs. per cubic yard. The aggregate portion provides the majority of the strength and weight to the concrete structure. Cement provides adhesion between the components and also fills in the voids between the aggregate compound particles. Sand is used to fill in the voids left between cement particles.
While conventional concrete structures provide good load bearing capability, they are prone to corrosion. For instance, pilings made from standard concrete do not possess a high degree of water impermeability. When concrete pilings are used in aquatic environments such as in or near fresh or salt water, the exposed concrete corrodes, thereby shortening the lifetime of the section and entire support structure. Other corrosive environments, such as chemical pools, also present the same obstacle.
Several techniques have been developed to protect concrete support structures from corrosive elements. For instance in the area of submerged concrete support structures, a protective steel jacket is placed around the concrete piling to provide a water-impermeable barrier between the water and the piling. However, the exposed steel jacket itself is prone to corrosion and requires cathodic protection. The total cost of the steel-jacketed concrete piling is very high due to the high materials cost of the steel jacket and the operating expense of providing cathodic protection.
Another technique which has been used to enhance the corrosion resistance of concrete support structures is the use of silica-mixed concrete. Silica-mixed concrete is standard concrete (described above) with a microsilica additive. The microsilica fills in the small gaps between cement particles, thereby imparting a high degree of impermeability to water, chemicals, solvents, or other concrete-corrosive materials. The resulting structure exhibits a higher resistance to corrosion than similar concrete structures without the microsilica additive.
Unfortunately, silica-mixed concrete is substantially more expensive than standard grade concrete, typically adding 75% to the cost of materials. As a consequence, silica-mixed concrete support structures have not been widely used in large-scale construction projects.
What is needed is a more economical concrete structure which exhibits high strength and corrosion resistance.
The present invention describes an economical, high strength, highly corrosion-resistant, multi-section concrete support structure and method of manufacture. In one embodiment of the invention, a multi-sectioned concrete support structure is presented and includes a first concrete section attached to a second concrete section. The first concrete section consists of a first concrete type and the second concrete section is above the first one, consists of a diverse, second concrete type. The diversity of concrete types in the support structure can be used to provide greater structural strength, increased resistance to concrete corrosion, decreased member weight, and lower cost compared to conventional homogeneous concrete support structures.